THUNDERSTORM T0008 Date: Sunday 31st August 1997 Time: 14:22 BST Location:
Macclesfield, Cheshire UK Path: Overhead moving north
Synoptics: Warm core
destabilisation along likely cold front Duration: Over an hour Type: Multicell Average lightning type: C-C / I-C (mostly invisible in daylight) Average discharge rate: 30 seconds Footage Quality: VHS
This storm was the strongest daytime storm of the year
for Macclesfield. It showed up on the precipitation radar as a big
orange/red blob about 50 miles in diameter as it moved northwards, a very
large cell. The rain was forced down by strong downdrafts and most of the
lightning was at the back of the storm, showing good vertical shear with
rearward development. There was one very strong C-C, possibly accompanied
with a close C-G/P-F near the end which gave a very loud thunder.
It was grey and drizzly
all day in a warm sector (the low looks ex-tropical with a warm core in the
satellite imagery). The storm occurred likely along a non-polar jet cold
front forced by an upper trough digging into the south of the low, as there
was a definite clearance to brighter weather and higher bases behind it. The
anvil became visible before a few more showers packed in closely behind it.
The lightning wasn't
very well captured on camera due to the fact most of it was happening to the
south (and I was filming northwards), and the rain was so intense in a
southerly that I didn't want to risk getting the camera wet by pointing it
in that direction. Another reason for not seeing the lightning very well,
apart from daytime brightness, was the thick and dense rain-curtains and
likely low cloud reducing the visibility further. Perhaps also with a storm
of this nature, it was mostly upper-anvil lightning. If this storm was at
night-time it would have been quite spectacular.